Fuel injectors for internal combustion engines



0. BRETING March 30, 1965 FUEL INJECTORS FOR INTERNAL COMBUSTION ENGINESFiled Oct. 19, 1962 2 Sheets-Sheet 1 2 Sheets-Sheet 2 ,lillll I'll-llINVENTOR ORNEYS O. BRETING March 30, 1965 FUEL INJECTORS FOR INTERNALCOMBUSTION ENGINES Filed 00L 19, 1962 nited States Patent 3,175,771Patented Mar. 30, 1965 fiice 3,175,771 FUEL INJECTORS FGR INTERNALCOMBUSTION ENGINES Olivier Brting, 5 Ave. Valiond, Sainte-Foy-les-Lyon,France Filed Oct. 19, 1962, Ser. No. 231,726 Claims priority,application France, Nov. 4, 1961, 42,961, Patent 1,312,045 1 Claim. (Cl.239-533) It is known that there is a constant search for improving thegrade of fuel atomization of a fuel injector of thermal engines, notablydiesel engines. In fact, in compression-ignition engines the ignitiontime period to which the quantity of fuel burned according to thedetonating process is subordinated depends very closely on the fuelinjection atomization fineness. As this quantity of detonating fuelinvolves simultaneously the characteristic and unpleasant noise ofdiesel engines together with a strong reduction in the engineefiiciency, it appears that the quality of the initial portion of thecombustion is of particular importance.

Now it was amply proved that this atomization quality could not beattained with conventional injection methods and means. In fact, in mostinstances the first drops of injected fuel must clear many constrictedor throttled passages successively so that their potential pressure isreduced and the final atomization occurring under a relatively lowpressure is particularly poor.

This invention relates to a closed, automatic fuel injector wherein thevalve member opens in the direction opposite to the fuel output, thusacting as a simple needlevalve device.

Tests have been made with a view to achieve in a needle valve injectorthe atomization and the necessary fluidtightness by means of the sameco-operating surfaces of the needle-valve and injection nozzle. Thismounting requiring a moderate valve lift for maximum efiiciency led toparticularly strict requirements regarding the valve spring; on theother hand, the composite mounting of the device made it particularlycostly and impaired therefore its marketability.

The fuel injector according to the present invention is of the valveneedle type wherein the valve face, by coacting with the registeringvalve seat formed on the nozzle, will on the one hand atomize the fuelwhen the needle valve is lifted and on the other hand provide thenecessary fluid-tightness when the needle valve is seated.

This last principle is already known per se and is set forth in detailin various works dealing with fuel injection. However, whatcharacterizes the fuel injector according to this invention is on onehand the fact that the injector nozzle consists of a single member andon the other hand that the needle valve is seated under the influence ofa lightweight yet powerful spring of which the action is coincident withthe needle-valve action.

This spring meets two requirements: on one hand its thrust is applieddirectly on the needle-valve in order to reduce the weight of movingparts during the needle valve movements, and on the other hand itsstiffness is such that the increase in the needle valve surface areassubjected to the injection pressure during the valve lift producesadditional efiorts incrementing the spring deflection by a height equalto the optimum lift of said needle valve. This lift is of the order of0.004" for a 60-degree needle valve.

It may be noted that the spring action, which as already stated iscoincident with the needle valve action and exerted in the direction ofthe valve axis, eliminates any side thrust in the needle valve movementsand therefore conventional sources of wear and tear which are a frequentcause of valve jamming.

Reference will now be made to the accompanying drawings of which FIGURE1 illustrates by way of example a typical embodiment of a fuel injectoraccording to this invention, and FIGURE 2 illustrates a secondembodiment thereof.

This device comprises a needle valve 1 similar to those of conventionalneedle-valve fuel injectors. The injection nozzle 2 may be consistentwith standard requirements concerning the manufacture of these parts.

One specific feature of the fuel injector according to this invention isthat the needle-valve face is such that its end portion 3, on thedownstream side of the needle valve, acts jointly as an atomizing nozzlewhen the fuel under pressure accumulating in chamber 5 has exerted anupward pressure on the thrust cone 6 suflicient to lift the valve.

In order to warrant a sufiicient strength to the nozzle at the level ofthis valve face, the nozzle is formed downstream of the outer-mostmeridian 3 of this face with an outfiaring surface 4, according to aknown arrangement now in general use in the manufacture of injectionequipment. The angle of this outflaring surface 4 is greater than thatof the injection jet in order to avoid any interference with this jet;however, an angle inferior to degrees is preferred.

If desired, a cavity may be substituted for this outflaring or taperedsurface, and in this case the cavity may have an optimum contour asdetermined by systematic tests. In fact, it is stated in certainconventional works dealing with fuel injection that under strictlydetermined conditions this cavity may play a substantial part in theatomization and improve the quality thereof.

The needle valve portion projecting from the atomizing nozzleconstitutes a useless cone which may be very sensitive to the hightemperatures attained in the combustion chamber. Therefore, this endportion may be truncated to increase the heat resistance.

According to a preferred embodiment of the injection device constitutingthe subject-matter of this invention,

,the light, strong spring exerting a constant force on the needle valvestem consists of a plurality of stacked dished washers, according to therules well known in the technical field.

The upper portion 8 of this washer stacking is prestressed by anadjustable stop member 9 solid with the fixed part on which the injectoris mounted, generally the so-called injector carrier (not shown).

The use of dished washers reduces to a minimum the weight of the movablecomponent elements of the injector, thus improving the operation of thedevice of this invention, which takes place as follows:

The pressure wave from the fuel pump (not shown) or another sourcereaches the chamber 5 through a passageway 10. When the pressure inchamber 5 has risen to a value such that the action exerted on thethrust cone 6 exceeds the force of spring 7, the needle valve is lifted.At this time the wet surface area increases very rapidly, thus reducingthe time period during which the atomization is rather poor, a fact wellknown to those conversant with the art, since the optimum requirementsfor a goodquality atomization are not met. Moreover, it is known thatthe optimum valve lift, corresponding to the tapered atomizing nozzle,is very low, of the order of 0.004". A valve lift of this value is thusrapidly attained and permits at the same time a direct atomization.Under these conditions it will be seen that as the pressure reaching theinject-or is absorbed completely for fuel atomizing purposes only theinjector according to this invention will effect quickly a high-gradeatomization, under optimum and high pressure conditions. This is thescope contemplated, which permits of reducing consider-ably the ignitiontime period constituting a very important element in the operation ofdiesel or compression-ignition engines. Actually, the noiselessness andeconomy of operation of diesel engines are to a large extent subordinateto this re- =duction in ignition time.

Conventionally, the tapered nozzle of this injector is improved by aslight centrifugal action. The latter may be created by incliningconduit 10 with respect to the vertical axis of the injector and alsowith respect to a plane through said vertical axis and the point ofintersection of said conduit 'with the chamber of said injector. Thisembodiment is shown at FIGURE 2, wherein the inclined or oblique conduitis referenced as 10', and the end 3 of the needle valve is truncated.

On the other hand, in order to reduce the weight of the movablecomponent elements of the injector the needle valve may be provided withvarious perforations 11 and/ or circular grooves 12 to constitute a kindof labyrinth and reduce injector leakages.

Any other suitable spring means capable of applying a centered andrelatively strong force with a moderate deflection may be substitutedfor the dished washers illustrated.

Of course, the principles of this injection device are also applicableto different types of injectors, such as long injectors,non-conventional injectors, etc. without departing from the spirit andscope of the invention. Besides, many modifications may be brought tothe specific form of embodiment illustrated, described-and suggestedherein without departing from the basic principles of the invention asset forth in the appended claim.

I claim:

An automatic fuel injector for thermal motors of the close typecomprising, a single axial needle valve having a conical tapered endportion and a thrust cone portion 3 and being adapted to open in adirection opposite the flow of fuel, a nozzle having a central channelwhich houses said needle, said nozzle having at its lower part afuelreceiving chamber into which there opens an oblique conduitcommunicating with the injector members for placing the fuel underpressure, said conduit being oblique with respect to the vertical axisof said injector and also with respect to a plane through said verticalaxis and the point of intersection of said conduit with the chamber ofsaid injector, and said nozzle having a seat below said chamber whichcooperates with the conical end of said needle, as

well as a frusto-conical shaped extension of the opening of said seatwith an angle greater than that of the jet of fuel, said needle beingsupported by a stack of washer springs acting directly at the top andthe said fuel-feed conduit opening into the said chamber obliquely atthe periphery of the latter so as to impart a centrifugalmovement to theliquid projected out of the chamber, and said thrust cone portion beingin the form of a conical tapered surface which defines a shoulder onwhich the accumulated fuel in said chamber exerts a pressure, therebylifting said valve.

References Cited by the Examiner UNITED STATES PATENTS 1,157,305 10/15Frost. 2,192,803 3/40 Purdy et al 239453 2,263,197 11/41 Tabb et a1.239-453 2,382,151 8/45 Harper.

FOREIGN PATENTS 97,829 9/24 Austria. 91,209 4/97 Germany. 474,978 4/29Germany.

20,758 9/11 Great Britain.

EVERETT W. KIRBY, Primary Examiner.

